Switching mechanism



Jan. 30, 1940. A. L. .JUDsoN ETAL SWITCHING MECHANISM Filed May 7, 1957 lll,

Patented Jan. 30, 1940 SWITCHING MECHANISM Albert L. Judson and Carl G. Kronmiller,

Minneapolis, Minn., assignors to Minneapolis- Honeywell VRegulator Company, Minneapolis, Minn., a corporation of Delaware Application May 7, 1937, Serial No. 141,300

14 Claims.

This invention relates to a switching mechanism and more particularly to that type of switching mechanism adapted to open and/or close an electrical circuit or circuits in accordance with changes in the value of a condition sumed by the movable contacts upon disengagement, such as misalignment occasioned by sticking.

A further object resides in the provision in a switching mechanism of a switch box comprising a relatively unitary self contained structure containing the iixed and movable contacts and including a cover so arranged that no circuit may be established through the switching mechanism unless the cover is in its proper position.

A further object is the provision of such a switch box adapted to contain a magnet or magnets to impart a relatively snap action to the movable contact, the magnets being so arranged as to form a substantially integral part of the switch box whereby the xed contacts, magnets and switch box may be positioned in the switching mechanism as a substantially integral unit.

An additional object resides in the forming and positioning of the magnets in such manner that they will exert a relatively maximum magnetic pull upon the movable contact mechanism and at the same time occupy substantially a minimum of space in the switch box.

A further and more specific object is the provision of a switching mechanism of the type to be hereinafter described which is durable, sturdy, reliable in operation and relatively inexpensive to manufacture.

Other objects will in part be obvious and in part be pointed out hereinafter,

The invention accordingly consists in the arrangements of parts, combination of elements and details of construction, all as will be point- 1 ed out more fully hereinafter and disclosed in the accompanying drawing wherein;

Figure l is a front elevational view of one form of structure embodying the instant invention,

Figure 2 is a side sectional view taken along (Cl. Zilli-67) the line 2-2 of Figure 1 as seen from the right,

Figure 3 is a side sectional view taken along the line 3--3 of Figure 4 as viewed from the bottom,

Figure 4 is a sectional view taken along the line 4-4 of Figure 3, certain portions omitted in Figure 3 being disclosed in Figure 4,

Figure 5 is an enlarged sectional view taken along the line 5-5 of Figure 3,

Figure 6 is an enlarged and elevational view of the structure shown in Figure 4, certain portions thereof being broken away,

Figure '7 is a perspective view of a switch box comprising a portion of the instant invention,

Figure 8 is a perspective view of a cover to be utilized in connection with the switch box shown in Figure '7, and

Figure 9 is an enlarged sectional view taken substantially along the line 9-9 of Figure l but disclosing the cover. in assembled relation withthe switch box.

Referring now to the drawing and more particularly to Figure 1 there is generally indicated at I0 a casing to which is secured as by screws I2, a housing II. Housing II is provided with an interiorly disposed peripheral flange I3 to which is secured one end of a bellows I4, the other end of bellows vI4 being secured to a plate I5. A depending boss I6 is integrally secured to the base of housing Il and provided with a passageway I'I extending therethrough. A capillary tube I8 threadedly engages boss I6 and extends to a suitable source of pressure (not shown) which may be positioned in any space, the pressure or other condition of which it is desired to control.

Secured to plate I5 is an operating rod I9 having a pointed tip 20. An annulus 2| positioned about operating rod I9 serves as a seat for one end of a coil spring 22, the other end of which abuts a flange 23, which comprises an integral portion of a stop 24, which latter serves to preclude collapse of bellows I4.

Thus it will be seen that changes in the condition value adjacent the condition responsive bulb are transmitted through tube I8 into casing II where such condition value fluctuations serve to expand or contract bellows I4 to move operating rod I9 upwardly or downwardly in a known manner. Spring 22 permits the instrument to operate at subatmospheric pressures, since it is. of suicient strength to bias operating rod I9 to its uppermost position, in the absence of a sui'liciently low pressure in housing II to occasion downward movement of bellows I4. It will arcane mally in substantial alignment with the vertical axis of arm 50.

Positioned adjacent arm 00 and surrounding contact carrying member 93 is a switch box 00 comprised of insulating material and provided with a relatively large aperture |0| in a Wall thereof to permit ingress and relatively free movement of arm 60. Metallic sleeves |02 are embedded in the insulating material comprising switch box |00 (see Figure 9) and provided with transversely extending threaded bores |03 adapted to accommodate threaded contact screws |04 having contact heads |05 and extremities |00 provided with slots to permit engagement of a tool therewith -to vary the position of contact heads |05. Contact heads |05 are so positioned as to be engageable by contact buttons 94 and 35 upon opposite sides of switch box |00. Thus it will be seen that springs serve further` to maintain a relatively firm contact pressure between contacts 94 and 95 and their associated contact heads |05, since the tendency of springs 10 is to urge contacts 94 and 95 in a direction towards contact heads and to yield resiliently as the contact pressure is increased thereby upon a movement of the contacts towards separation, maintaining a comparatively constant contact pressure until such time as the contacts are separated.

It should here be pointed out that contacts 94 and 95 are provided with convex contact surfaces as are also contact heads |05 whereby if sticking occurs between a contact 94 or 95 and either of its associated contact heads |05, a rocking motion of contact carrying member 93 about the axis previously mentioned, in alignment with rivets 92,' will pry the contacts apart. Springs 95 serve to restore contacts 94 and 95 to their proper position of alignment for reengagement with their associated contact heads 95 upon release of such sticking.

A pair of magnets |0 having relatively beveled inclined edges l |0a are positioned in suitable recesses Ill in casing |00 and held in position as by transversely extending bars ||2 engaged by screws ||3. Magnets ||0 serve to impart a relatively rapid or snap action to movement of contact carrying member 93 and its associated contacts through their action on member 9| and bar 98, as member 93 is moved in the manner previously described from the influence of one magnetic iield to the other. Magnets ||0 are, as better shown in Figure l, positioned at an angle with respect to contact carrying member 93. Inclined edges I0a, however, aresubstantially parallel to member 93 and thus exert a relatively great magnetic force thereon, considerably greater than would be exerted were the magnets' of conventional shape and so inclined, since, as will be understood, the allocation of the magnetic field upon member 9| or bar 98 increases as the adjacent member aproaches the surface of the magnet and due to the fact that surfaces ||0a are relatively parallel to the vadjacent surfaces of member 9| and bar 98, the closest approach is permitted. The inclination, however, permits the magnetsto be disposed in a relatively compact space and at the same time permits a relatively wide clearance at the lower portions thereof, as viewed in Figure l, to permit free movement of arm 50.

Metallic sleeves |02 are, as better shown in Figure 9, similarly provided with additional threaded bores |20 at substantially right angles to bores |03. In each of bores |20 is positioned a set screw |2| of a length insuillcient to completely ll the bore which serves to preclude accidental rotation of contact screws |04. The upper extremity of sleeves |02 extend to, and if desirable, slightly above the adjacent surface of insulating material comprising switch box |00. A cover |30 is provided with downwardly extending portions |29 comprising ridges adapted to engage suitable recesses |26 (see Figure l'7) formed in switch box |00. Additional recesses |25 are also formed in the side walls of switch box |00 to provide clearance for the heads |06 of contact screws |04 when cover |30 is in position. Cover |30 is provided with a plurality of metallic bushings |32 having apertures |3| therethrough. Bushings |32 are so positioned as to be in substantial registry and physical contact with the upper extremities of bores |20 of sleeves |02. Screws |40 are, as best shown in Figure 9, adapted to pass through apertures |3| and threadedly engage bores |20 above set screws |2|. Suitable outside wiring connections |4| may lead from screws I 40 to any desired condition control mechanism (see Figure 9).

Thus from the foregoing it will be seen that removal of cover |30 from switch box |00, which may be accomplished only by the release of screws |40, serves to break any possible circuit through the mechanism. It will also be seen that such circuit may not be reestablished until cover |30 is repositioned and properly secured by screws |40 to switch box |00. Thus should it become necessary to adjust any of the mechanism contained lwithin switch box |00 it becomes impossible for the adjuster thereof to receive any electrical shock from any circuit through the mechanism. It is further impossible to accidentally close any circuit as by bridging the contacts with a screw driver or other tool. Additionally the use of cover |30 serves to protect the interior mechanism and prevent. to a large extent, the ingress of dirt and foreign matter thereto. However, ready access may be had to the contact structure merely by removing cover |30 in the manner above mentioned.

Thus from the foregoing it will be seen thatthere is herein provided a structure which accomplishes the objects of this invention and others in an improved and advantageous manner and which includes many advantages of great practical importance.

Since many embodiments may be made of the above invention and since many modifications may be made in the embodiment above described it is to be understood that all matter herein described or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. A contact structure for use in a switching mechanism comprising, in combination, an arm, a member, means pivotally securing said member to said arm at an intermediate point, contacts carried by said member adjacent each extremity, leaf springs associated with said means on either side of said member normally biasing the same into substantial alignment with said arm but yieldable to permit pivotal movement thereof upon the application of force to either of said contacts and servingl to restore said alignment upon the abatement of said force.

2. A contact structure for use in a switching mechanism comprising, in combination, an arm having an aperture therein, a member, means loosely securing an intermediate portion of said member to said arm, a contact disposed adjacent each extremity of s aid member, said member being so arranged that one of said contacts is positioned in said aperture, said loosely securing means permitting pivotal movement of said member and hence said contacts with respect to said arm, said one of said contacts moving through said aperture upon such pivotal movement and resilient means normally biasing said member and hence said contacts into substantial'alignment. with said arm and hence positioning said one of said contacts in said aperture, said resilient means being adapted to yield upon the application of force to either of said contacts but restore said alignment on abatement of said force.

3. In a switching mechanism, in combination, a rst contact, a second contact movable into and out of engagement with said iirst contact, means to move said second contact, said means including an arm, means loosely mounting said second contact on said arm, oppositely directed protruding bearing surfaces carried by said arm, and resilient means on each side of said mounting means for normally holding said second `contact in alignment with said arm, whereby, upon sticking of said rst and second contacts a pivotal movement about said bearing surfaces is imparted to said second contact upon movement of said arm in a direction. away from said rst contact to cause rotative movement oi'` said second contact with respect to said iirst contact to release said sticking, said resilient means serving to return said contact to said alignment upon such release.

4. in a switching mechanism, in combination, plurality of xed contacts, an arm, means to move said arm, a member loosely mounted at an intermediate point on said arm, contacts carried by each extremity oi said member adapted to engage said xed contacts, oppositely directed abutment means carried by said arm, and resilient means on each side of said member normally biasing said member into alignment with said arm but yieldable upon the application oi force to said member to permit pivotal movement oi said member about said abutment means on said arm, whereby upon sticmng or one of said contacts carried by said member, and its associated nxed contact, rotative movement is imparted to said contact carried by said member through said member to release said sticking, said resilient means restoring said member to said alignment upon such release.

5. In a switching mechanism, in combination, a switch box having an aperture therein, a movable arm extending through said aperture, means to move said arm, a contact carried by said arm, a second contact carried by said switch box, a cover for said switch box, a securing member on said cover for engaging said switch box and holding said box and cover in related assembly, leads engaging said securing member' and forming part of an electrical circuit which includes said xed and said movable contacts, and a conductive path between said xed contact and said securing member whereby said circuit maybe closed only when said cover is positioned on said switch box and secured thereto by said securing means.

6. In a switching mechanism, in combination, a switch box having an aperture therein, a movable arm extending through said aperture, means to move said arm, a contact carried by said arm, a second contact carried by said switch box, a cover for said switch box.- a. securing member on saidswitchboxsndholding said box and cover inrelated assembly, leads engaging said securing member and forming part of an electrical circuit which includes said fixed and said movable contacts, and a conductive path between said fixed contact and said securing member whereby said circuit may be closed only when said cover ispcsitioned on said switch box and secured thereto by said securing means, said securing member comprising a screw, and said conductive path a metallic threaded sleeve in electrical association with said fixed contact and positioned for engagement by said screw.

7. In a switching mechanism, in combination, a switch box having an aperture therein, a movable arm extending through said aperture, means to move said arm, a Contact carried by said arm, a second contact carried by said switch box, a cover for said switch box, a securing member on said cover for engaging said switch box and holding said box and cover in related assembly, leads engaging said securing member and forming part of an electrical circuit which includes said fixed and said movable contacts, and a ccnductive path between said fixed contact and said securing member whereby said circuit may be closed only when said cover is positioned on said switch box and secured thereto by said securing means, said securing member comprising a screw, and said conductive path a metallic threaded sleeve in electrical association with said fixed contact and positioned for engagement by said screw and a set screw positioned in said sleeve to secure said fixed contact in a given position, said set screw being relatively short and adapted to be completely encased in said sleeve whereby said rirst screw may be threaded into said sleeve subsequent to insertion of said set screw therein.

8. in a switching mechanism, in combination, a switch boxy of insulating material having an aperture therein, a movable arm extending through said aperture, means tomove said arm, contacts carried by said arm, sleeves of conductive material embedded in said insulating material, additional contacts positioned for enl gagement with said first mentioned contacts in electrical engagement with said sleeves, a cover for said switch box also of insulating material, and having apertures therein positioned for registry with said sleeves, metallic members passed through said apertures and engaging in said sleeves comprising part of an electrical circuit incuding said xed and said movable contacts, wiring secured to said members in the exterior of said cover, whereby said xed contacts, said s sleeves and said members form a conductive path to said wiring to form an electrical circuit when said xed and movable contacts are in engagement, and removal of said members and/or said cover means breaks said circuit regardless of the position of said contacts.

' 9. In a switching mechanism, in combination, a switch box of insulating material having an aperture therein, a movable arm extending through said aperture, means to move said arm, contacts carried by said arm, sleeves of conductive material embedded in said insulating material, additional contacts positioned for engage- .ment with said rst mentioned contacts in electrical engagement with said sleeves, magnetic means secured in said casing adjacent said iixed contacts to impart a snap action to the movement of said movable contacts into and out of engagement with said fixed contacts, a cover for saidswitch box also of insulating material,

and having apertures therein positioned for registry with said sleeves, metallic members passed through said apertures and engaging in said sleeves thereby comprising part of an electrical circuit including said fixed and said movable contacts, wiring secured to said members on the exterior of said cover, whereby said fixed contacts, said sleeves and members form a conductive path to said Wiring to form an electrical circuit when said xed and movable contacts are in engagement, and removal of said members and/or said cover means breaks said circuit regardless of the position of said contacts.

10. In a switching mechanism including iixed and movable contacts and means to move said first mentioned contacts, a xed contact containing receptacle comprising a casing and a cover therefor of insulating material, contacts embedded in said casing, securing means holding said cover and said casing in related assembly, means forming a conductive path between said contacts and said securing means and leads xed to said Isecuring means, whereby said leads, securing. means and contacts form a conductive path'which is broken by disassembly of said casing and cover.

11. In a switching mechanism including fixed and movable contacts and means to move said iirst mentioned contacts, a iixed contact containing receptacle comprising a casing and a cover therefor of insulating material, contacts embedded in said casing, securing' means holding said cover and said casing in related assembly, means forming a conductive path between said contacts and said securing means and leads xed to said securing means, whereby said leads, securing means and contacts form a conductive path which is broken by disassembly of said casing and cover and a magnet carried by said easing to impart a snap action to the movement of said movable contacts, whereby said casing, contacts,

magnet cover and securing means may be preassembled as a substantially unitary relatively compact structure.

12. A contact structure for use in a switching mechanism comprising in combination, an arm having a straight portion and an oifset portion, a member loosely carried by said offset portion, a contact mounted on said member, a stationary contact positioned for cooperation therewith, two leaf springs, one on each side of said member normally maintaining it in line with the straight portion of said arm, and means about which said member can fulcrum as said arm moves into or out of contact closing position.

13. A contact structure for use in a switching mechanism comprising in combination, an operating arm, a contact carrying member pivotally secured to said arm, a contact carried by an extremity of said member, and spring means carried by said arm on each side of said member for normally holding said member in substantial alignment with said arm but yieldable to permit pivotal movement of said member when a force is exerted on said contact.

14. In a switching mechanism, in combination, a casing, a stationary Contact mounted within said casing, a second contact mounted for movement into and out of engagement with said stationary contact, an opening in said casing providing access to said contacts, a cover for said casing closing said opening and thereby preventing access to said contacts, circuit connections to said contacts, and means for breaking the circuit to said contacts as a direct result of the removal of said cover.

ALBERT L. JUDSON.

CARL G, KRONMILLER- 

